The previous version of the TfL Business Plan was published in March by the outgoing Mayor. It specifically mentioned the Metropolitan line extension, indeed the project had its own paragraph. The new draft Business Plan has nothing.

The 'vision for the London Underground' in the previous version specifically mentioned the Northern and Metropolitan line extensions. The new draft Business Plan mentions only the Northern and the Bakerloo.

In the appendix to the new draft Business Plan we learn that the Northern line extension is due to cost £612m over the five years from 2017 to 2022. We learn that the Barking Riverside extension is due to cost £82m over the same period. But the list doesn't mention the Metropolitan line extension at all, even though contributory funding from Hertfordshire County Council and the DfT is already confirmed.

The Metropolitan line extension was due to link the existing Watford branch to Watford Junction via a new viaduct and a disused railway line. Trains would no longer serve the current terminus at Watford Met, but two new stations would be built at Cassiobridge and Watford Vicarage Road. Or at least that was the plan.

The Metropolitan line extension was given the go-ahead by government five years ago this week, with Hertfordshire County Council originally in control. They found running the project difficult, with the end result that budgets rose and timescales slipped. Last year full responsibility for the extension was handed from HCC to London Underground, with the project due for completion by the end of 2020.

And now it seems that London Underground have decided not to proceed. They might have kicked the project so far into the future that it falls outside the scope of a five year business plan, but that seems unlikely. They might have decided there's insufficient money for the extension, and published the draft Business Plan hoping nobody will notice. Or they might have accidentally forgotten to mention it, and all is still on track.

Here's why I don't think the omission is an accident.

Every three months TfL hold a Community Liaison Group to discuss the Metropolitan line extension with a panel of local stakeholders, and the minutes of these meetings are posted on the project's webpage. In the latest minutes, dated 5th October 2016, we learn that the project is being held up while TfL try to find a new construction partner.

Nothing has happened on site since that liaison meeting except some minor work relating to the diversion of two sewers and a few BT cables. I've even been down and looked. Much vegetation has already been cleared and the trackbed has been levelled, but no construction vehicles are present and no start on the key connecting viaduct has been made. While TfL reconsider their finances and escalating costs, any work of any physical significance has been put on hold.

Most tellingly, the minutes contain this exchange between Philip Brading (Three Rivers councillor, and Chair) and Paul Judge (TfL's acting lead for the Metropolitan line extension project).

In other words, when the councillor asked in October whether the new Mayor was still interested in the project, he was told to wait for publication of the Mayor's Transport Strategy. We now have that document, in the form of the TfL Business Plan, and the Metropolitan line extension gets absolutely no mention whatsoever. The only logical conclusion is that the Metropolitan line extension is no longer a priority, and has been dropped.

If that is the case, it's enormously disappointing. A project that's been on the drawing board for 40 years, and funded for five, has slipped silently back into oblivion. It's also perhaps not unexpected. Sadiq's fare freeze has put TfL's finances under enormous pressure, so it was always looking likely that a major project would have to be cut. And it's also highly embarrassing. Sadiq has made a big thing of being trustworthy enough to take over suburban rail services around the capital, and here he is scrapping a project just outside London transferred to him by the local county council.

As a Croxley boy, born and bred, I'd very much like to be wrong. I'd like to hope that the omission of the Metropolitan line extension from the draft TfL Business Plan is nothing more than an administrative error, but it appears to be more deliberate than that. Who deleted it, and why, and when were they thinking of telling us?